One known type of information storage device is a disk drive device that uses magnetic media to store data and a movable read/write head that is positioned over the magnetic media to selectively read from or write to the magnetic media.
FIG. 1a provides an illustration of a typical disk drive device. The disk drive device has a series of magnetic hard disks 101, a spindle motor 102 for spinning the disks 101, and a drive arm 104 with a head gimbal assembly (HGA) 100 mounted thereon. The HGA 100 includes a magnetic recording head 103 with a read/write head (not shown) embedded therein. A voice-coil motor (VCM, not labeled) is provided for controlling the motion of the drive arm 104 and, in turn, controlling the magnetic recording head 103 to move from track to track across the surface of the disks 101, thereby enabling the read/write head to read data from or write data to the disks 101. Moreover, the disk drive device also includes a load/unload device that commonly is a ramp 105 for loading/unloading the magnetic recording head 103. When the disk drive device operates, a lift force is generated by the aerodynamic interaction between the magnetic recording head 103 and the spinning magnetic disks 101. The lift force is opposed by equal and opposite spring force which is applied by the HGA 100 such that a predetermined flying height above the surface of the spinning disks 101 is maintained over a full radial stroke of the drive arm 104.
Now referring to FIGS. 1b-1c, a conventional HGA 100 comprises the magnetic recording head 103, a suspension 190 to load or suspend the magnetic recording head 103 thereon. As illustrated, the suspension 190 includes a load beam 206, a base plate 208, a hinge 207 and a flexure 205, all of which are assembled together.
The load beam 206 is connected to the base plate 208 by the hinge 207. A locating hole 212 is formed on the load beam 206 for aligning the load beam 206 with the flexure 205. As best shown in FIG. 1c, a dimple 211 is formed on the load beam 206 to transfer load forces generated by the load beam 206 to the flexure 205 at a position corresponding to a center of the magnetic recording head 103. By this engagement of the dimple 211 with the flexure 205, the load forces can be transferred to the magnetic recording head 103 uniformly, thus making the magnetic recording head 103 working more stably.
The base plate 208 is used to enhance structure stiffness of the whole HGA 100. A mounting hole 213 is formed on the end of the base plate 208 for mounting the whole HGA 100 to the drive arm 104 (refer to FIG. 1a). The hinge 207 has a mounting hole 210 formed on its one end corresponding to the mounting hole 213 of the base plate 208, and the hinge 207 is partially mounted to the base plate 208 with the mounting holes 210, 213 aligned with each other. The hinge 207 and the base plate 208 may be mounted together by laser welding at pinpoints 209 distributed on the hinge 207. Two hinge steps 215 are integrally formed at two sides of the hinge 207 at one end adjacent the mounting hole 210 for strengthening stiffness of the hinge 207. In addition, two hinge struts 214 are extended from the other end of the hinge 207 to partially mount the hinge 207 to the load beam 206.
The flexure 205 runs from the hinge 207 to the load beam 206. The flexure 205 has a proximal end 238 adjacent the hinge 207 and a distal end 216 adjacent the load beam 206. The flexure 205 of the suspension 190 also has a suspension tongue 236 with which almost an entire surface of one face of the magnetic recording head 103 comes in contact with and fixed. A locating hole 217 is formed on the distal end 216 of the flexure 205 and aligned with the locating hole 212 of the load beam 206, thus obtaining a high assembly precision.
FIG. 1d shows the tip part of the HGA 100 on which the magnetic recording head 103 is mounted. The suspension tongue 236 is also referred to as a gimbal whose one end is connected to the flexure 205, and the connection part exhibits a spring characteristic which functions to allow the loaded magnetic recording head 103 to keep a proper flying height with respect to the disks 101.
The suspension tongue 236 and the magnetic recording head 103 are securely fixed by an adhesive filled therebetween. Further, there are cases of using solder for fixing the magnetic recording head 103, whether or not the adhesive is used.
As illustrated in FIGS. 1d-1e, a plurality of electrical traces 304 is formed on the flexure 205 along length direction thereof. One end of the electrical traces 304 are electrically connected to six electrical pads 303 which are formed on the suspension tongue 236 and another end of the electrical traces 304 are electrically connected to a preamplifier (not shown). A trailing surface 305 of the magnetic recording head 103 has six bonding pads 301 corresponding to the six electrical pads 303. Concretely, the bonding pads 301 are electrically connected to the electrical pads 303 by solder joints 302, thus connecting to the electrical traces 304, thereby electrically connecting the magnetic recording head 103 to the electrical traces 304. When the magnetic recording head 103 is mounted on the suspension tongue 236 and electrically coupled with the electrical traces 304 by the bonding pads 301, the preamplifier controls the magnetic recording head 103, thus realizing data reading/writing operation with respect to the disks 101.
In the prior art, due to the size of the magnetic recording head 103, the number of the bonding pads 301 formed on the trailing surface 305 of the magnetic recording head 103 are normally six. Moreover, another two bonding pads 301 of the magnetic recording head 103 are disposed outside the magnetic recording head 103. During the process of producing the magnetic recording head 103, all the bonding pads 301 are adapted for both bonding the magnetic recording head 103 to the suspension 190 of the HGA 100 and testing the performance of the magnetic recording head 103. Concretely, among the bonding pads 301 formed on the magnetic recording head 103, a pair of the bonding pads 301 is electrically connected to a reading element (not shown) for reading data from the disks 101, a pair of the bonding pads 301 is electrically connected to a writing element (not shown) for writing data to the disks 101, and a pair of the bonding pads 301 are electrically connected to a thermal resistance (not shown) for heating a pole tip formed on an air bearing surface of the magnetic recording head 103 which facing to the surface of the disks 101. Further, the pair of the bonding pads 301 disposed outside of the magnetic recording head 103 is electrically connected to a sensor (not shown) for inducting the affection between magnetic recording head 103 and the disks 101 and then adjusting the flying height of the magnetic recording head 103.
However, firstly, because the pair of the bonding pads 301 electrically connected to the sensor is placed outside the magnetic recording head 103, the flying height of the magnetic recording head 103 can not be adjusted immediately when the sensor is inducting the affection between the magnetic recording head 103 and the disks 101 and, in turn, affecting the reading/writing performance of the magnetic recording head 103. Secondly, in order to meet the request of the testing, the size of the bonding pads 301 is as big as the size of a probe of the testing device. And due to the small room and the size of the magnetic recording head 103, it is difficult to place other bonding pads with additional functions on the trailing surface of the magnetic recording head 103 and, in turn, the function or performance of the magnetic recording head 103 is limited. Thirdly, due to the small space between a bonding pad and the adjacent bonding pad, it is easy to create a short circuit therebetween, thus damaging the magnetic recording head 103.
Hence, there is a need for an improved magnetic recording head, head gimbal assembly and disk drive unit that do not suffer from the above-mentioned drawbacks.